1. The Field of the Invention is compound chamber rotary positive displacement motors with a high expansion ratio. Sub-fields of interest are, (a) an effective cooling system, (b) operation of the device as a compressor, (c) a compact power plant, and (d) unloading the timing gears from the gas forces.
2. Description of the Prior Art
Compound chamber rotary motors: U.S. Pat. No. 1,164,546 is for a rotary motor with serial expansion chambers. The high pressure (HP) chamber is axially spaced from the larger expansion chamber. The HP rotors have a long wrap helix. Great Britain Pat. No. 1317 is for a serial expansion motor whose HP rotors have groove-type HP chambers. Combining elements from the two devices gives a compound chamber motor somewhat like the present invention. U.S. Pat. No. 715,221 is a rotary motor with compound expansion chambers. A groove-type HP chamber feeds a larger expansion chamber from which it is separated by a rotating flange. There is no meshing channel in the gate rotor for the flange. U.S. Pat. No. Re. 29,627 and USSR Pat. No. 840,414 are compressors in which groove-shaped communication channels are carved out of the main bulk of one rotor. The other rotor has flanges meshing with the grooves. The grooves are not HP chambers. A rotary compressor with groove-type HP chambers is shown in "POWER", June 1977, pp. S-18 and 19. This device has undercut piston shapes. Cooling systems in rotary positive displacement devices: German Pat. No. 1,125,445 has passages through the housing apex where mesh begins, for spraying coolant at the hot parts. U.S. Pat. No. 3,518,975 mentions coolant injection passages through the water jacket. The cooling scheme proposes liquid jets "coordinated to the displacement chambers". U.S. Pat. No. 3,181,292 shows liquid streams released by the piston rotor upon one end of the hot piston faces. In French Pat. No. 1,175,287, liquid jets through piston recesses spray the hot parts.
Rotary motors with integral compressors: U.S. Pat. Nos. 2,485,687 and 3,188,800 are two examples, with screw rotors, exhaust gas scavenging, and air compression at the back of the motor.